Undesirable high door latch release effort can be caused by frictional force between ratchet and pawl engagement. It is known that the friction force on engagement is directly related to a contact frictional coefficient and an automotive door seal load. Current state of the art systems for reducing friction between the ratchet and pawl can include a double pawl configuration, special low friction grease, and/or low friction plating. However, there remain disadvantages of the magnitude of release effort for these current systems, as well as undesirable noise of operation and manufacturing complexity.
Further disadvantages with current state of the art systems include required numerous different latch designs as different versioned arrangements of ratchet and pawl to suit different design constraints of latch operation depending upon the particular vehicle door configuration and latch footprint constraints. The ability to have a customizable latch design using similar ratchet and pawl components is desired, in order to match varying requirements in operational and/or footprint characteristics.
One prior art latch design is U.S. Pat. No. 5,941,579 that describes a pin slidably mounted within a guideway of a latch housing, such that the pin is positioned for rotation between a detent fork of a ratchet and a pawl of the latch. Disadvantages of this system relate to the type and magnitude of friction generated between the pin and the adjacent surfaces of the ratchet and pawl. Further, alignment of the ratchet with the pawl can be problematic for the overall operation of the latch. This art also positions the pin on the latch housing, something that can be inconvenient for different housing package designs of different automotive door/hood configurations.